1. Field of the Invention
The present invention relates to antennas for transceiver apparatus and more particularly to an antenna for cellular telephone frequencies that is adapted to be mounted to a window of a vehicle.
2. Description of Related Art
It has long been known that an antenna can be mounted on a pane of glass and that the dielectric properties of the glass can be advantageously be used to capacitively couple the antenna to the radio apparatus when they are on opposite sides of the glass. The patent to J. A. Rostron, U.S. Pat. No. 1,715,952, issued June 4, 1929 taught a window mounted antenna that was capacitively coupled through the window to a transmitting or receiving apparatus.
With the popularity of radios in automobiles, several early inventors patented antennas which were mounted on vehicular windows or windshields. Typical of these are the patents to M. Diamant, French Patent No. 1.314.455, issued Dec. 3, 1963, the German patents to P. L. R. Eaubonne, No. 25 43 973, issued Apr. 8, 1976, and to A. C. R. Braglia, No. 25 38 290, issued Apr. 29, 1976, and the U.S. Pat. No. 4,089,817 to D. Kirkendall.
More recently, a patent was issued to D. L. Parfitt, U.S. Pat. No. 4,238,799, issued Dec. 9, 1980 which reflected the strong interest in citizens band radios which had achieved great popularity and were in widespread use. The antenna disclosed therein was an electrically shortened, inductively loaded half wave antenna adapted to be installed on a non-conductive surface of a vehicle. The electrically shortened half-wave antenna was chosen because of the unavailability of a ground plane which would permit the use of the more desirable, quarter-wave length ground plane antenna.
In recent years, the cellular telephone has become an extremely popular accessory item in vehicles. The cellular telephone is a transceiver operating in a frequency range of from 820-895 MHz. At these frequencies, one wavelength can be approximately one foot, thereby allowing virtually any antenna length to be chosen.